DS2120

6 of 10

Table 1. PIN DESCRIPTION

DS2120E 28-Pin TSSOP

PIN

NAME

DESCRIPTION

1

VREF

Regulator Output Voltage. 1.25V reference in LVD mode; must be

decoupled with a 4.7µF cap.

2–5, 7–12,

18–21, 23–26

RxP, RxN

Signal Termination. Connect to SCSI bus signal lines.

6, 22

HS_GND

Heat Sink Ground. Internally connected to the mounting pad. Should be

connected to ground.

13

ISO

Isolation. When pulled high, terminating resistors and biasing current sources

are isolated from the SCSI bus.

14

GND

Signal Ground.

15

MSTR/SLV

Master/Slave. Mode select for the noncontrolling terminator. When pulled

high (MSTR), the DIFFSENS driver is enabled.

16

DIFFSENSE

DIFFSENSE. Output to drive the SCSI bus DIFFSENS line.

17

DIFF_CAP

DIFFSENSE Capacitor. Connect a 0.1

µF capacitor for DIFFSENSE filter.

Input to detect the type of device (differential or single -ended) on the SCSI

bus.

27, 28

TPWR

Termination Power. Connect to the SCSI TERMPWR line and decouple with

2.2

µF capacitor.

DS2120B 36-Pin SSOP

PIN

NAME

DESCRIPTION

1

VREF

Regulator Output Voltage. 1.25V reference in LVD mode; must be

decoupled with a 4.7µF cap.

2, 3, 33, 35

NC

No Connect. Do not connect pins.

4–7, 11–16,

22–25, 29–32

RxP, RxN

Signal Termination. Connect to SCSI bus signal lines.

8–10, 26–28

HS_GND

Heat Sink Ground. Internally connected to the mounting pad. Should be

connected to ground.

17

ISO

Isolation. When pulled high, terminating resistors and biasing current sources

are isolated from the SCSI bus.

18

GND

Signal Ground.

19

MSTR/SLV

Master/Slave. Mode select for the noncontrolling terminator. When pulled

high (MSTR), the DIFFSENS driver is enabled.

20

DIFFSENSE

DIFFSENSE. Output to drive the SCSI bus DIFFSENS line.

21

DIFF_CAP

DIFFSENSE Capacitor. Connect a 0.1

µF capacitor for DIFFSENSE filter.

Input to detect the type of device (differential or single ended) on the SCSI

bus.

34

LVD

Low-Voltage Differential. Output of DIFFSENSE receiver; output high

indicates LVD bus operation .

36

TPWR

Termination Power. Connect to the SCSI TERMPWR line and decouple with

2.2

µF capacitor.